200 lines
5.4 KiB
XML
200 lines
5.4 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!--
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====================================================================
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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====================================================================
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-->
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<!DOCTYPE document PUBLIC "-//APACHE//DTD Documentation V1.1//EN"
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"../dtd/document-v11.dtd">
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<document>
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<header>
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<title>HPSF THUMBNAIL HOW-TO</title>
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<authors>
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<person name="Drew Varner" email="Drew.Varner@-deleteThis-sc.edu" />
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</authors>
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</header>
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<body>
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<section><title>The VT_CF Format</title>
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<p>Thumbnail information is stored as a VT_CF, or Thumbnail Variant. The
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Thumbnail Variant is used to store various types of information in a
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clipboard. The VT_CF can store information in formats for the Macintosh or
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Windows clipboard.</p>
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<p>There are many types of data that can be copied to the clipboard, but the
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only types of information needed for thumbnail manipulation are the image
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formats.</p>
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<p>The <code>VT_CF</code> structure looks like this:</p>
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<table>
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<tr>
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<th>Element:</th>
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<td>Clipboard Size</td>
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<td>Clipboard Format Tag</td>
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<td>Clipboard Data</td>
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</tr>
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<tr>
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<th>Size:</th>
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<td>32 bit unsigned integer (DWord)</td>
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<td>32 bit signed integer (DWord)</td>
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<td>variable length (byte array)</td>
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</tr>
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</table>
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<p>The Clipboard Size refers to the size (in bytes) of Clipboard Data
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(variable size) plus the Clipboard Format (four bytes).</p>
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<p>Clipboard Format Tag has four possible values:</p>
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<table>
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<tr>
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<th>Value</th>
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<th>Identifier</th>
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<th>Description</th>
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</tr>
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<tr>
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<td><code>-1L</code></td>
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<td><code>CFTAG_WINDOWS</code></td>
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<td>a built-in Windows© clipboard format value</td>
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</tr>
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<tr>
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<td><code>-2L</code></td>
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<td><code>CFTAG_MACINTOSH</code></td>
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<td>a Macintosh clipboard format value</td>
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</tr>
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<tr>
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<td><code>-3L</code></td>
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<td><code>CFTAG_FMTID</code></td>
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<td>a format identifier (FMTID) This is rarely used.</td>
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</tr>
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<tr>
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<td><code>0L</code></td>
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<td><code>CFTAG_NODATA</code></td>
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<td>No data This is rarely used.</td>
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</tr>
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</table>
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</section>
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<section><title>Windows Clipboard Data</title>
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<p>Windows clipboard data has four image formats for thumbnails:</p>
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<table>
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<tr>
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<th>Value</th>
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<th>Identifier</th>
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<th>Description</th>
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</tr>
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<tr>
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<td>3</td>
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<td><code>CF_METAFILEPICT</code></td>
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<td>Windows metafile format - recommended</td>
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</tr>
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<tr>
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<td>8</td>
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<td><code>CF_DIB</code></td>
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<td>Device Independent Bitmap</td>
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</tr>
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<tr>
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<td>14</td>
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<td><code>CF_ENHMETAFILE</code></td>
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<td>Enhanced Windows metafile format</td>
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</tr>
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<tr>
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<td>2</td>
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<td><code>CF_BITMAP</code></td>
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<td>Bitmap - Obsolete - Use <code>CF_DIB</code> instead</td>
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</tr>
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</table>
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</section>
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<section><title>Windows Metafile Format</title>
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<p>The most common format for thumbnails on the Windows platform is the
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Windows metafile format. The Clipboard places and extra header in front of
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a the standard Windows Metafile Format data.</p>
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<p>The Clipboard Data byte array looks like this when an image is stored in
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Windows' Clipboard WMF format.</p>
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<table>
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<tr>
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<th>Identifier</th>
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<td>CF_METAFILEPICT</td>
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<td>mm</td>
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<td>width</td>
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<td>height</td>
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<td>handle</td>
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<td>WMF data</td>
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</tr>
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<tr>
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<th>Size</th>
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<td>32 bit unsigned int</td>
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<td>16 bit unsigned(?) int</td>
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<td>16 bit unsigned(?) int</td>
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<td>16 bit unsigned(?) int</td>
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<td>16 bit unsigned(?) int</td>
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<td>byte array - variable length</td>
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</tr>
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<tr>
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<th>Description</th>
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<td>Clipboard WMF</td>
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<td>Mapping Mode</td>
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<td>Image Width</td>
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<td>Image Height</td>
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<td>handle to the WMF data array in memory, or 0</td>
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<td>standard WMF byte stream</td>
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</tr>
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</table>
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</section>
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<section><title>Device Independent Bitmap</title>
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<p><strong>FIXME:</strong> Describe the Device Independent Bitmap
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format!</p>
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</section>
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<section><title>Macintosh Clipboard Data</title>
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<p><strong>FIXME:</strong> Describe the Macintosh clipboard formats!</p>
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</section>
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</body>
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</document>
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-->
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